Tourists wait in line at the heliport of Air Zermatt for a flight by airlift into the valley to Raron, in Zermatt, on Jan. 9, 2018. Due to heavy snowfall and rain showers, Zermatt can only be reached by air.Dominic Steinmann / Keystone via AP

About 13,000 tourists were trapped in the popular Swiss ski resort Zermatt Matterhorn for a second straight day Tuesday as officials warned of "large and, in many cases, very large dry avalanches."

In a statement, the famed resort also warned: "There are possible power breakdowns all over Zermatt."

Police and operators in the area closed roads leading in and out of the region on Monday morning and canceled all train services Monday night. Hiking and skiing in the area, about 75 miles east of Geneva, was also banned.

The decision to cut off access to the resort was made after the Swiss Federal Institute for Forest, Snow and Landscape Research raised the avalanche risk level to 5 — the maximum.

"Numerous large and, in many cases, very large natural dry avalanches are to be expected as a result of fresh snow and strong winds," the institute warned on its website. "Without question, it is inadvisable to engage in ski touring, freeriding and snowshoe hiking outside marked and open pistes."

"There's no way in or out of town right now," said John Lauria of New York City, who was visiting Zermatt with his sister, Amanda.

"We were only skiing on Sunday. Monday and Tuesday were too much avalanche risk," Lauria told NBC News. "Today, they didn't allow anybody on the mountain whatsoever."

Still, there are worse places to be stranded, he said.

"There's enough cheese in this town to feed all of America for a full year," he said. "And let me tell you, there's no shortage of beer, Champagne and other fine wines. We've been good. Sauna, massages, shopping, let me tell you: Not a big deal."

Amanda Lauria said: "Everyone seems to have a positive attitude and is looking forward to the skiing conditions tomorrow."

Zermatt can be reached only by air because of heavy snow and rain showers. Swiss authorities have closed ski slopes, hiking trails, cable cars, roads and train service into the town of Zermatt.Mateusz Bocian / EPA

New snowfall Monday evening coated layers of old snow, creating a perfect environment for avalanches, the institute said.

Resort operators said that the measures were preventive and sensible under the circumstances and that there was no immediate threat to guests and residents.

"There are about 13,000 tourists at the moment that are spending the holiday here," Janine Imesch, a spokeswoman for Zermatt, told NBC News. "The situation is under control, and there are no safety issues."

Agence France-Presse estimated that the resort has a resident population of 5,500 people.

"Level 5 is almost unheard of in Zermatt," the Matterhorn Diamonds private ski school, which is based at the resort, warned in a tweet. It urged its customers to take care.